Abstract The objective of this work was to evaluate the influence of colored shade mesh and plant density on the morphological characteristics of Corymbia citriodora seedlings. The highest radiation efficiency was found in the blue mesh, 7.01 g MJ-1 and 5.72 g MJ-1 for average and high density respectively. For dry matter and leaf area index at high density, the treatment without mesh followed by the red mesh was the best. The chlorophyll index did not differ between treatments, with mean values of 206.4, 59.1 and 262.0 for chlorophyll a, b and total, respectively. Using principal component analysis, we found the total variance to be 70%. The use of colored shade mesh and plant density altered the radiation use efficiency and dry matter accumulation. Leaf area index was affected only by plant density. The red mesh resulted in the most similar values to the treatment without mesh.

Aeglids are freshwater anomurans that are endemic from southern South America. While their population biology at the species-level is relatively well understood, intraspecific variation within populations has been poorly investigated. Our goal was to investigate the population biology of Aegla platensis Schmitt, 1942 from the Uruguay River Basin, and compare our data with data from other populations. We estimated biometric data, sex ratio, population density and size-class frequencies, and frequencies of ovigerous females and juveniles, from the austral spring of 2007 until autumn 2008. Sexual dimorphism was present in adults, with males being larger than females. Furthermore, males and females were significantly larger than previously recorded for the species. The overall sex ratio was 1.33:1 (male:female), and population density ranged from 1.8 (spring) to 3.83 ind.m-² (winter). Data from this population differ from published information about A. platensis in almost all parameters quantified except for the reproductive period, which happens in the coldest months, and a population structure with two distinct cohorts. Difference among studies, however, may be in part due to methodological differences and should be further investigated in order to determine their cause. In addition to different methodologies, they may result from ecological plasticity or from the fact that the different populations actually correspond to more than one species.

O tamanho da primeira maturação sexual (TPM) em Aegla platensis Schmitt, 1942 foi estimado através das mudanças nas proporções de dimensões corporais dos animais. Para isso, foram realizadas coletas mensais, de julho de 2007 a junho de 2008 no Lajeado Bonito (27º25'27''S, 53º24'39''W), um tributário de primeira ordem do Rio da Várzea, município de Frederico Westphalen, Rio Grande do Sul. Foram utilizados 437 machos com comprimento de cefalotórax (CC) variando de 6,00 mm a 31,75 mm e 368 fêmeas, com tamanhos entre 6,08 mm e 27,92 mm de CC. As seguintes dimensões corporais foram mensuradas em todos os indivíduos coletados: comprimento do cefalotórax (CC), largura do abdome (LA), comprimento do própodo do quelípodo direito (CPD) e comprimento do própodo do quelípodo esquerdo (CPE). Após o registro dessas medidas, os animais foram devolvidos ao mesmo local de captura. As análises de maturidade sexual morfológica foram realizadas com auxílio do software Mature 2, nas quais foram utilizadas as medidas de CC, considerada como variável independente e relacionada com as demais dimensões. As relações que melhor se ajustaram para estas análises, em machos, foram CPD x CC (TPM: CC=18,2 mm) e CPE x CC (TPM: CC=20,1 mm) e LA x CC (TPM: CC=16,5 mm) nas fêmeas.

The size at the onset of morphological sexual maturity (SOM) of the anomuran crab Aegla platensis Schmitt, 1942 was estimated through the changes in the ratios of corporal dimensions of the animals. For this, aeglids were monthly collected, from July 2007 to June 2008 in Lajeado Bonito (27º25'27''S, 53º24'39''W), a first order tributary of the rio da Várzea, in Frederico Westphalen municipality, state of Rio Grande do Sul, Brazil. Samples of 437 males and 368 females were used, with cephalothorax length (CC) ranging from 6.00 mm to 31.75 mm in males and from 6.08 mm to 27.92 mm in females. The following corporal dimensions of collected individuals were measured: cephalothoracic length, abdomen width (LA), length of the right propodus cheliped (CPD), length of the left propodus cheliped (CPE). After the register of these measures, the crabs were returned to the stream, to the same places where they were collected. Estimation of the size at the onset of morphological maturity was performed using the Mature 2 software. The most appropriated relations for this analysis in males were CPD x CC (SOM: CC=18.2 mm) and CPE x CC (SOM: CC=20.1 mm) and for females LA x CC (SOM: CC=16.5 mm).